In many industries, it is commonplace to provide thermal insulation for pipe and equipment to prevent heat loss or gain. When insulation on pipe and equipment are exposed to the external environment, the insulation material can become wet leading to its physical deterioration, loss of thermal efficiency, and corrosion of the pipe or piece of equipment being insulated. Therefore, an additional outer layer, commonly called a protective jacketing (sometimes also referred to as a lagging or cladding), is installed over the insulation to provide it with weather protection and protection from physical abuse. Currently, the insulation field is lacking protective jacketing constructions whereby the jacketing can be pre-applied to an insulation, and then transported as pre-jacketed insulation construction to an industrial job site such that the construction can be easily, quickly, and efficiently installed on pipe and/or equipment in the field.
Typically, protective jacketing materials, in the form of materials such as sheet metal, plastic sheet, metal foil / plastic laminates, or metal foil / fiberglass cloth laminates, are not adhered to industrial insulation in a factory, prior to transporting the materials to the industrial site. Rather, the insulation materials are first transported to the industrial site, installed on the pipe and/or equipment, and then the protective jacketing is installed separately over top of the insulation. The two are then simply fastened or banded together. The reason the material transport and material installation is done in this sequence is because most industrial insulation surfaces are dusty and fibrous in nature. These characteristics give an insulation surface that is dusty which contains loose fibers and hence, do not allow for direct bonding of the insulation to a protective jacketing. Therefore, the installation process at the industrial site is inherently slow and labor intensive. The protective jacketing must be installed and sealed in a separate step, after the insulation has been installed and restrained with tape or wires or bands.
The practice of the insulation contracting industry is to transport insulation materials and protective jacketing to the industrial job site, then install the insulation on the pipe or equipment, securing it in place with tape, wire or bands, followed by a separate protective jacketing installation step. A drawback of this process is when the insulation and protective jacketing are fastened together, gaps, however miniscule, remain between the protective jacketing overlaps, from one sheet of jacketing to the next, or on the lap joints where the jacketing circumscribes the circular pipe insulation. The movement of the protective jacketing relative to the insulation and the insulated surface, caused by pipe or equipment movement and/or differential thermal expansion and contraction, prevents a true seal. The lack of a seal allows for the possibility of gaps through which water, or other electrolytes, can enter the insulation itself and be absorbed or condensed onto the insulation, leading to CUI. The present invention addresses these shortcomings by first providing an industrial insulation amenable for direct bonding to a protective jacketing.
It would be desirable to provide insulation amenable for bonding or adhering uniformly to a protective jacketing. Such an insulation substrate would preclude the possibility of movement of a jacketing, once the insulation-jacketing construction is installed on a pipe or piece of equipment. This would allow application of a protective jacketing in a factory setting, which would dramatically decrease installation time and costs in the field (e.g., by reducing tools, labor and materials). Prior to the present inventors' discovery, due to the friable nature of many insulation materials, a protective jacketing had to be manually installed on the thermal insulation at the site of the pipe or equipment that required insulation. A protective jacketing-insulation material composite structure serves to secure the protective jacketing-insulation bond from disturbance under typical industrial conditions. The present invention addresses these and other needs.
Corrosion of metal pipe or piece of equipment under insulation, known as corrosion under insulation (CUI), presents a major problem for most process industries, including, but not limited to, petroleum, chemical, food and paper. In many instances, corrosion of pipe or equipment is not determined until system failure. Pipe or equipment leakage, catastrophic damage caused by such leakage, significant operational downtime and high maintenance costs are all effects CUI.
Although corrosion is easily diagnosed by looking at the exterior surface of a pipe or piece of equipment, insulation and protective jacketing on the outer surface of the pipe or equipment insulation presents an optical, barrier to the pipe or piece of equipment. Because water intrusion to the insulation is unpredictable, CUI is also highly unpredictable, so inspection has to encompass the entire insulated system in order to be effective. Corrosion of a particular segment of a pipe or piece of equipment, therefore, can be both costly and arduous to decipher.
For corrosion to occur on a metal pipe or piece of equipment, there must be (1) an anode, (2) a cathode, (3) an electrical path caused by a potential difference between the anode and cathode, and (4) an electrolyte. Inherent to all metals are an anode, cathode and electrical path (i.e., the metal surface of the pipe or piece of equipment). Speed and frequency of transfer of electrons between the anode and cathode correlates with the tendency of a pipe or piece of equipment to corrode, and will differ based on material of the pipe or piece of equipment, its contents, system operating temperature, etc. Although CUI can be inhibited somewhat at the outset by choosing one substrate over another, the substrate will still be susceptible to CUI if electrolytes are introduced via damp insulation. It is not always cost feasible to replace existing pipe or piece of equipment, so the substrate cannot always be selected. It is of particular concern, therefore, to limit electrolytes (in most cases water), from interaction with insulation surrounding a pipe or piece of equipment, and the pipe or piece of equipment itself, by sealing the insulation from the external environment. The present invention addresses this need.
There are methods to detect CUI before system failure, such as removing insulation, followed by inspection of the pipe or piece of equipment, utilizing moisture density gauges and infrared surveys. These methods are time consuming, costly, and in many cases, require operational downtime. Detection efforts can be limited by implementing systems which employ composite structures comprised of a protective jacketing over insulation. This solution, if provided correctly (i.e., a uniform interface between the protective jacketing and insulation), would limit the CUI inspection costs of an industrial system because no vapor could be trapped between the protective jacketing layer and the insulation layer. Current methods for providing a protective jacketing allow for the protective jacketing to move, and consequently, do not provide a seal from the external environment. For example, metal bands have been used to attach an aluminum jacket to pipe insulation; these restrain the insulation and the metal jacket to the pipe but do not preclude intrusion of water at the joints, where the jacketing material overlaps itself or the adjacent section. This technique leaves at least a gap between the insulation's exterior surface and the jacket, which in turn permits movement of the jacket and intrusion of water.